Development of an online two-dimensional nano-scale liquid chromatography/mass spectrometry method for improved chromatographic performance and hydrophobic peptide recovery

An online two-dimensional (2D) strong cation-exchange (SCX)/reversed-phase (RP) nano-scale liquid chromatography/mass spectrometry (nanoLC/MS) method was developed for improved separation and hydrophobic peptide recovery. Sharper and more symmetric RP peaks were observed with the use of a "band re-focusing method", in which an analytical RP column with more hydrophobicity than the RP trap column was used in the system. To recover hydrophobic peptides still unreleased from the SCX column after a conventional salt step gradient due to hydrophobic interaction, a RP step gradient from 10% to 30% acetonitrile (ACN) was applied to the SCX column in the presence of a high salt concentration following the salt gradient. There were 301 unique hydrophobic E. coli peptides identified from the RP fractions. These peptides, which were 19% of all E. coli peptides identified from a 2D run, would not have been identified without the application of the RP gradient to the SCX column.     

The pathological response to DNA damage does not contribute to p53-mediated tumour suppression

The p53 protein has a highly evolutionarily conserved role in metazoans as 'guardian of the genome', mediating cell-cycle arrest and apoptosis in response to genotoxic injury. In large, long-lived animals with substantial somatic regenerative capacity, such as vertebrates, p53 is an important tumour suppressor--an attribute thought to stem directly from its induction of death or arrest in mutant cells with damaged or unstable genomes. Chemotherapy and radiation exposure both induce widespread p53-dependent DNA damage. This triggers potentially lethal pathologies that are generally deemed an unfortunate but unavoidable consequence of the role p53 has in tumour suppression. Here we show, using a mouse model in which p53 status can be reversibly switched in vivo between functional and inactive states, that the p53-mediated pathological response to whole-body irradiation, a prototypical genotoxic carcinogen, is irrelevant for suppression of radiation-induced lymphoma. In contrast, delaying the restoration of p53 function until the acute radiation response has subsided abrogates all of the radiation-induced pathology yet preserves much of the protection from lymphoma. Such protection is absolutely dependent on p19(ARF)--a tumour suppressor induced not by DNA damage, but by oncogenic disruption of the cell cycle.     

On the spectra luminescence properties of charoite silicate

Charoite is a hydrous alkali calcium silicate mineral [K₄NaCa₇Ba_0.75Mn_0.2Fe_0.05(Si₆O₁₅)₂(Si₂O₇)Si₄O₉(OH)·3(H₂O)] exhibiting an intense lilac colour related to Mn²⁺ and Fe³⁺ colour centres. These ions also contribute to a strong luminescence at ∼585 and 705 nm. This work studies the thermal dependence of these luminescent centres by (i) thermoluminescence (TL) of pre-heated and pre-irradiated charoite aliquots, (ii) by time-resolved cathodoluminescence (TRS-CL) at room and cryogenic temperatures (RT and CT), (iii) by spatially resolved spectra CL under scanning electron microscopy (SRS-CL-SEM) and (iv) by ion beam spectra luminescence (IBL) with H⁺, H₂⁺ and ⁴He⁺ ions at RT and LT. The main peak, ∼585 nm, is linked to a transition ⁴T_1,2 (G)→⁶A₇(S) in Mn²⁺ ions in distorted six-fold coordination and the emission at ∼705 nm with Fe²⁺→Fe³⁺ oxidation in Si⁴⁺ lattice sites. Less intense UV-blue emissions at 340 and 390 nm show multi-order kinetic TL glow curves involving continuous processes of electron trapping and de-trapping along with an irreversible phase transition of charoite by de-hydroxylation and lattice shortening of Δa=0.219 Å, Δb=0.182 Å; Δc=0.739 Å. The Si-O stressed lattice of charoite has non-bridging oxygen or silicon vacancy-hole centres, and Si-O bonding defects which seem to be responsible for the 340 nm emission. Extrinsic defects such as the alkali (or hydrogen)—compensated [AlO₄/M⁺] centres could be linked with the 390 nm emission. Large variations in 585 and 705 nm intensities are strongly temperature dependent, modifying local Fe-O and Mn-O bond distances, short-range-order luminescence centres being very resistant under the action of the heavy ion beam of ⁴He⁺. The SRS-CL demonstrates strong spatial heterogeneity in the luminescence of the charoite.     

Antideuteron yield at the AGS and coalescence implications

We present Experiment 864's measurement of invariant antideuteron yields in 11.5A GeV/c Au+Pt collisions. The analysis includes 250x10(6) triggers representing 14x10(9) 10% central interactions sampled for events with high mass candidates. We find (1/2pip(t))d(2)N/dydp(t) = 3.5+/-1.5(stat)+0.9-0.5(syst)x10(-8) GeV-2 c(2) for 1.8 = 0.35 GeV/c ( y(c.m.) = 1.6) and 3.7+/-2.7(stat)+1.4-1.5(syst)x10(-8) GeV-2 c(2) for 1.4 = 0.26 GeV/c, and a coalescence parameter B2; of 4.1+/-2. 9(stat)+2.3-2.4(syst)x10(-3) GeV2 c(-3). Implications for coalescence and antimatter annihilation are discussed.     

Synthesis of novel fused β-lactams by intramolecular 1,3-dipolar cycloadditions.51. Triazolocephems and triazolopenams

Tricyclic triazolocephem and triazolopenam carboxylic acids have been synthesized, but only the former exhibited antibacterial activity.     

Detection of acceptor sites on human lymphocytes for antigen-specific T cell factors.

Mouse antigen-specific T cell factors are absorbed by human peripheral blood lymphocytes at acceptor sites. The acceptors are products of HLA-linked genes, which may be human immune response genes.     

Direct chemolysis-gas chromatography-mass spectrometry for analysis of paint materials

A novel direct method using (m-trifluoromethylphenyl)trimethylammonium hydroxide (TFTMAH) has been developed for on-line (trans)esterification of lipidic materials (drying oils, egg) prior to GC-MS analysis. The method was first optimised by comparing three N-methylammonium hydroxide reagents (TMAH, PhTMAH, TFTMAH) and triolein as a lipid standard. Secondly, the procedure was tested on a series of fresh and naturally aged (up to 40 years) (un)pigmented drying oils and egg yolk reference film standards. Thirdly, the method was applied to the analysis of a sample from an altar painting "Resurrection of Christ" by Francesco Solimena (1723) from the Chapel of Upper Belvedere in Vienna. The relative proportions of the fatty acids from the translucent size layer confirm the presence of partially degraded oil, probably prepolymerised walnut oil.